Don’t leave the door hanging on hinges when painting. For a smooth finish without drips and runs, lay it flat and remove all the hardware including hinges and knobs. Both sides can be painted in a day if the door is laying across sawhorses and rests on lag screws. Drill a 1/4-in. hole in the base and two at the top, and turn 3/8-in. x 3-in. lag screws 1 1/2-in. into the door. Spread the sawhorses so it rests entirely on the bolts. Paint one side, then hold the top two screws to rotate the door on the single base screw.

Step 2: Keep It Clean

Cleaning the door is the most important step to ensure good paint adhesion and a smooth finish. Using heavy-duty household cleaner, scrub the entire door to remove oily smudges and dirt, especially around the knob and at the base. Let it dry completely before filling any holes.

Step 3: Scrape and Sand

Remove flaking paint with a scraper then sand to smooth the edges. Sanding by hand tends to be better than using a power sander as high-speed sanding can melt paint and make it more difficult to smooth out. If the house was built before 1970, check paint for lead with a testing kit, from hardware stores for $10-$18.

Step 4: Smooth Out Flaws

New paint doesn’t hide tiny dents and scratches. In fact, it tends to highlight minor flaws. Fill shallow holes, scratches and dents less than 1/8-in. deep with spackling compound. For deeper holes, use a putty knife to apply two-part filler or an epoxy wood filler. You need to prep your door with as much detail as you would prepping your walls.

Step 5: Prime Time

Avoid spot priming as it makes the topcoat appear blotchy. Use a gray-tinted primer when covering an old color or painting on a new color other than white. After the primer dries, shine a strong light across the door to check the surface for missed scratches or dents. Cover flaws with more spackling compound, sand and re-prime these areas.

Step 6: Sand It Smooth

For the smoothest topcoat, sand the door by hand after the primer and between coats. Sand with non-clogging 180- or 220-grit sandpaper, using a sanding sponge for shaped areas. With the door flat on the sawhorses, this is a quick job that should take about five minutes. Brush or vacuum, then wipe down with a damp cloth to remove dust.

Step 7: Roll On the Finish

The best way to avoid brush marks is to avoid using brushes. Use foam rollers for both primer and paint to spread paint smoothly. Edge in around windows and panels with a brush, then coat the rest of the door using a 4-in. or 6-in. roller. Since they spread a thinner coat than conventional rollers or brushes, do two coats. Or you can get really professional (and much costlier) by using an airless spray sprayer to paint with. Although for just one door, it’s a bit overkill.